http://www.ck12.org Chapter 10. Chi-Square
X^2 =∑
i( (^0) i−Ei)^2
Ei
where:
X^2 =Chi-Square statistical value
O=observed frequency value
E=expected frequency value
5.Using the Chi-Square statistic and the level of significance, we are able to determine whether to reject or fail to
reject the null hypothesis and write a summary statement based on these results.
Supplemental Links
Distribution Tables (including the Student’s t-distribution and Chi-Square distribution)
http://www.statsoft.com/textbook/stathome.html?sttable.html&1
Review Questions
- What is the name of the statistical test used analyze the patterns between two categorical variables?
a. the Student’s t-test
b. the ANOVA test
c. the Chi-Square test
d. the z-score - There are two types of Chi-Square tests. Which type of Chi-Square test estimates how closely a sample
matches an expected distribution?
a. the Goodness-of-Fit test
b. the Test for Independence - Which of the following is considered a categorical variable:
a. income
b. gender
c. height
d. weight - If there were 250 observations in a data set and 2 uniformly distributed categories that were being measured,
the expected frequency for each category would be:
a. 125
b. 500
c. 250
d. 5 - What is the formula for calculating the Chi-Square statistic? The principal is planning a field trip. She samples
a group of 100 students to see if they prefer a sporting event, a play at the local college or a science museum.
She records the following results: